Comparison of Electromigration in Cu Interconnects with Atomic-Layer- or Physical-Vapor-Deposited TaN Liners

Abstract

Electromigration in 0.07 m wide Cu interconnections has been investigated for sample temperatures from 213 to 300°C. The effect of atomic-layer-or physical-vapor-deposited TaN x and physical-vapor-deposited Ta liner layers in Cu damascene lines on electromigration was also studied. A lower lifetime and activation energy for electromigration was observed in tested lines with sidewall voids. Similar electromigration lifetime and activation energy observed from samples with either atomic-layer-or physical-vapor-deposited TaN x suggested that the dominant diffusion paths in the Cu lines were not sensitive to the TaN x layer and were along the Cu/dielectric interface and/or grain boundaries.

Effect of NH3/He Plasma Treatment on Electromigration Behavior and Electrical Reliability of Copper Interconnects

“…As the width of Cu interconnects further decreases in the generation of semiconductor manufacturing technology below 65 nm, the drastic increase in current density within Cu wires will lead to a severe EM issue and accelerate the failure of microelectronic devices. Thus in the last decade, many studies have been performed to enhance the resistance of Cu interconnect structures to EM degradation and consequently to improve the reliability of devices (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18). Some factors influencing the EM behaviors of Cu atoms in interconnect structures have been reported.…”

“…(ii) The microstructure of interconnects (9)(10)(11): a bamboo-like structure in wires with grain boundaries perpendicular to electron flow reduces the diffusion paths of Cu atoms; twin boundaries inhibit the migration of Cu atoms. (iii) Diffusion barriers (12,13): barrier layers that induce the formation of strong (111) texture in wires enhance EM resistance. (iv) Capping layers (14,15): a strong adhesion between capping layers and Cu wires retards the diffusion of atoms along interfaces, such as a CoWP capping layer exhibiting a good EM resistance (16).…”

Ultrathin (AlCrTaTiZr)N[sub x]/AlCrTaTiZr Bilayer Structures with High Diffusion Resistance for Cu Interconnects

“…Because Cu has poor wettability with most nitride films and easily agglomerates or decoheres at high temperatures, 27 some structural defects for rapid Cu electromigration subsequently form. 29 Thus, in this work, a metallic AlCrTaTiZr film as a buffer layer is deposited on these barriers to construct ͑AlCrTaTiZr͒N 0.7 /AlCrTaTiZr and ͑AlCrTaTiZr͒N 1 /AlCrTaTiZr bilayers, to improve the interface adhesion to Cu, and to lower the average electrical resistivity of the barriers. The diffusion resistance of the bilayer structures is verified by characterizing the interdiffusion behaviors of Si and Cu at high temperatures reaching 900°C.…”

Effect of NH[sub 3]/He Plasma Treatment on Electrical Reliability and Early-Stage Electromigration Behavior of Copper Interconnects

“…Thus, in the past decade, many studies have been performed to enhance the resistance of Cu interconnect structures to EM degradation and consequently to improve the reliability of the devices. [6][7][8][9][10][11][12][13][14][15][16][17][18] Some factors influencing the EM behaviors of Cu atoms in interconnect structures have been reported. ͑i͒ The size of the interconnects: [6][7][8][9] Many grain boundaries and defects in large-sized wires lead to severe EM; a large difference between the sizes of wires and vias induces a high stress gradient and shortens the lifetime of the interconnects.…”

“…͑ii͒ The microstructure of the interconnects: [9][10][11] A bamboolike structure in wires with grain boundaries perpendicular to electron flow reduces the diffusion paths of Cu atoms; twin boundaries inhibit the migration of Cu atoms. ͑iii͒ Diffusion barriers: 12,13 Barrier layers that induce the formation of a strong ͑111͒ texture in wires enhance EM resistance. ͑iv͒ Capping layers: 14,15 A strong adhesion between capping layers and Cu wires retards the diffusion of atoms along interfaces, such as a CoWP capping layer exhibiting a good EM resistance.…”